High chroma effect materials

ABSTRACT

A color effect material is described as composed of a plurality of encapsulated substrate platelets in which each platelet is encapsulated with a highly reflective silver layer which acts as a reflector to light directed thereon, a spacer layer which is selectively transparent to light directed thereon, and an iron oxide layer on the spacer layer.

BACKGROUND OF THE INVENTION

[0001] The provision of metallic effects in surface coatings, plasticscoloration, cosmetic preparations and the like is well known. To achievethis effect, one approach has been to disperse both a metallic pigmentand a transparent colored pigment in the composition. The metallicpigment is usually aluminum flake and the colored pigment can be, forinstance, iron oxide. The art has also combined the two pigments into asingle entity by precipitating the colored material on the aluminumflake.

[0002] The precipitation of, for instance, iron oxide on the aluminumflake was often carried out from an aqueous solution but that gave riseto various difficulties. Aluminum readily reacts in aqueous media, verydilute solutions of the iron oxide were required, complexing additiveswere necessary and the procedure had to be carried out in a limited pHrange.

[0003] An alternate, non-aqueous procedure is described in U.S. Pat. No.4,328,042. Here, iron pentacarbonyl is oxidized to iron oxide and carbondioxide in a fluidized bed of the aluminum flake with oxygen at elevatedtemperature. To obtain reproducible results, the carbonyl cannot exceed5 volume percent of the fluidizing gas. The use of the low concentrationcarbonyl and fluidized bed operation are obvious drawbacks of thisapproach.

[0004] It is desirable to provide a color effect material (CEM) whichhas the same or better pigment properties as the products justmentioned, particularly a high chroma, but without encountering theproduction and materials limitations of that prior art. The presentinvention is directed to satisfying that desire.

SUMMARY OF THE INVENTION

[0005] The present invention provides a high chroma effect materialcomprising a platelet-shaped substrate encapsulated with: (a) a highlylight reflective first layer of silver, (b) a spacer layer of metaloxide, nitride, fluoride or carbide or polymer; whose refractive indexis sufficiently high to minimize the incident angle dependent variablepathlength difference, in accordance with Snell's Law, or thin enough tonot be optically active; (c) an iron oxide layer, and optionally, (d) alight transparent layer which is either the same or a different metal asin the first layer or a spacer layer material different from that in thespacer layer and whose refractive index is higher than that of thespacer layer material. The effect material, where necessary, can begiven a post-treatment for specific attributes such as weatherstability, polymeric dispersability and cosmetic compatibility. Themethod of producing the effect material pigment is also a part of thisinvention.

DESCRIPTION OF THE INVENTION

[0006] It is an object of the present invention to provide novel metaleffect materials which can also be prepared in a reliable, reproducibleand technically efficient manner. This object is achieved by an effectmaterial comprising a platelet-shaped substrate coated with: (a) ahighly light reflective silver first layer; (b) a spacer layer; (c) aniron oxide layer, and optionally, (d) a light transparent overlayer.

[0007] Any encapsulatable smooth platelet can be used as the substratein this invention. Examples of usable platelets include mica, aluminumoxide, bismuth oxychloride, boron nitride, glass flake, ironoxide-coated mica or glass, silicon dioxide and titanium dioxide-coatedmica or glass. The size of the platelet-shaped substrate is not criticalper se and can be adapted to the particular use. In general, theparticles have average largest major dimensions of about 5-250 microns,in particular 5-100 microns. Their specific free surface area (BET) isin general from 0.2 to 25 m²/g.

[0008] The degree of reflectivity for the first silver encapsulatinglayer, the highly reflective layer, should be at least about 75% and ispreferably at least about 90% reflectivity.

[0009] The thickness of the first layer is not critical so long as it issufficient to make the layer highly reflective. If desirable, thethickness of the first layer can be varied to allow for some selectivetransmission of light. The thickness is usually about 2 to 100 nm andpreferably about 10 nm to 75 nm. The mass percent of this coating canvary considerably because it is directly related to the surface area ofthe particular substrate being utilized and the thickness necessary toachieve the desired reflectivity. In general, the silver thicknessshould be at least about 5 nm, preferably from about 10 to 75 nm. Athickness of outside of the above-mentioned ranges will typically beeither completely opaque or allow for substantial transmission of light.

[0010] As a result of the high reflectivity, the silver encapsulatedsubstrate is substantially opaque and much more light is reflected thanwith conventional effect pigments. The amount of light reflected in thecase of, for instance, iron oxide-coated mica is on the order of about18% whereas the amount of light in the effect pigment of the instantinvention is on the order of 35%.

[0011] The high chroma effect material of the present invention containsa spacer layer encapsulation of the first encapsulating layer of silver.The spacer layer is usually composed of metal, metal oxide or hydroxide(other than iron), nitride, fluoride, or carbide or polymer. One canutilize any material for the spacer layer as long as it does not resultin more than 100 degrees of hue angle color travel in accordance withSnell's Law. Examples of suitable materials include chromium oxide,silicon dioxide, magnesium fluoride, magnesium oxide, magnesiumhydroxide, aluminum oxide, aluminum hydroxide, zinc oxide, zinchydroxide, zirconium oxide, zirconium hydroxide, titanium oxide,titanium hydroxide, titanium nitride, and polymers such as polymethylmethacrylate, polyethylene terephthalate and high density polyethylene.Preferably, the material is silicon dioxide (SiO₂), a suboxide ofsilicon dioxide (SiO_(0.25) to SiO_(1.95)) or magnesium fluoride.

[0012] The spacer layer material and the thickness of the layer areselected such that the layer does not provide a significant incidentangle dependent variable pathlength difference in accordance withSnell's Law, i.e., does not result in more than 100 degrees of hue anglecolor travel. Therefore, the particular thickness of the layer is notimportant so long this criteria is met. One convenient way to meet thisrequirement is to make the layer suitably thin. For example, materialshaving a refractive index around 1.5 should have a film thickness of nomore than 100 nanometers so as to not generate hue angle color travel ofmore than 100 degrees. When the layer is of silicon dioxide or magnesiumfluoride, it preferably has a thickness of about 25 to 75 nm. For alayer material having a high refractive index, such as for iron oxide ortitanium dioxide, the layer can be any thickness sufficient to producethe desired result.

[0013] Incident angle dependent variable pathlength difference isrelated to the degrees of hue angle change when changing the view fromnormal incidence to a high specular angle. The thickness of the layer,its refractive index, and Snell's law all contribute to the incidentangle dependent variable pathlength difference. The pathlength, whichdetermines the color, is calculated by the equation 2(n)(d) Cos θ₂,where n is the refractive index, d is the thickness in nm and θ₂ is therefraction angle. The refraction angle θ₂ is determined by Snell's lawn₁Sin θ₁=n₂ Sin θ₂, where n₁ is the refractive index of the incidentmedium (here the reflecting layer), n₂ is the refractive index of the(spacer) layer, and θ₁ is the incident angle. A spacer layer with highrefractive index would therefore not produce large differences in θ₂with increasing θ₁ and would not produce significant pathlengthdifferences. A layer with a low refractive index on the other hand,would produce large differences in θ₂ with increasing θ₁ and wouldproduce significant pathlength differences unless the layer thickness istoo thin to produce thin film interference. Thus, the spacer layer willnot produce a significant incident angle dependent variable pathlengthdifference when it has a high refractive index and/or it is too thin toproduce thin film interference. The purpose of the spacer layer is toprovide non-limiting decorative and/or functional attributes such ascolor, adhesion promotion, and film stress relief.

[0014] The effect material of the present invention contains an ironoxide layer directly encapsulated on the spacer layer. The thickness ofthis layer can vary considerably. As the thickness increases,interference colors are realized. In general, the layer thickness isabout 40 to 200 nm, and preferably about 60 to 180 nm.

[0015] The optional, outer encapsulating layer, when present, is amaterial providing a transparency of about 25-75% transmission. Morepreferably, one would prefer to have about 40-60% transparency for theouter encapsulating layer. The degree of reflectivity and transparencyfor the different layers can be determined using a variety of methodssuch as ASTM method E1347-97, E1348-90 (1996) or F1252-89 (1996), all ofwhich are substantially equivalent for the purposes of this invention.

[0016] The material employed as the outer layer can be selected from thesame group as the materials of the reflecting layer. Alternatively, theouter layer may also be a metal oxide (other than iron oxide), nitrideor carbide provided that it is different than that of the spacer layerand also has a higher refractive index.

[0017] The materials of the invention are notable for multipleencapsulation of the platelet-shaped substrate. In one embodiment, thesilver layer, spacer layer and iron oxide layer are encapsulated by aselectively-transparent outer layer that allows for partial reflectionof light directed thereon. Preferably, the outer encapsulating layer isselected from the group consisting of silicon, chromium oxide, a mixedmetal oxide, titanium dioxide, titanium nitride and aluminum, so as therefracive index is higher than the spacer layer. More preferably, theouter layer is one or more precious metal or alloys thereof.

[0018] The optional outer layer is, of course, a part of the opticalpackage. Its thickness can vary but must always allow for partialtransparency. For instance, the layer has a preferable thickness ofabout 5 to 20 nm for silicon; about 2 to 15 nm for aluminum; about 1-15nm for titanium nitride; about 10 to 100 nm for chromium oxide; about10-200 nm for titanium dioxide; about 5 to 60 nm for a mixed metaloxide, about 5 to 20 nm for silver; about 3 to 20 nm for gold; about3-20 nm for platinum; and about 5 to 20 nm for palladium. The metalalloys generally have a similar film thickness compared to the puremetal. It is recognized that a film thickness out of the above range maybe applicable depending on the desired effect.

[0019] All the encapsulating layers of the effect material of theinvention are altogether notable for a uniform, homogeneous, film-likestructure that results from the manner of preparation according to theinvention.

[0020] One advantage of the present invention is that one does not haveto start with a traditional metal flake which may have structuralintegrity problems, hydrogen outgassing problems and a host of otherperceived issues (pyrophoric and environmental concerns) typicallyassociated with metal flakes. The silver used in this invention is muchmore chemically stable than aluminum and generally prefer to be in itsnon-oxidized metallic ground state. Furthermore, silver can maximize thechromaticity of the reflected color(s) of the iron oxide. In addition,when silver is used as the final (outer) layer of the particle, it mayimpart electrical conductivity to the effect material which may bedesirable in some applications such as powder coatings.

[0021] While the metal layers can be deposited by any known means, theyare preferably deposited by electroless deposition and the non-metallayers preferably by aqueous or non-aqueous sol-gel deposition. Anadvantage of electroless deposition (Egypt. J. Anal. Chem., Vol. 3,118-123 (1994)) is that it is a worldwide established chemicaltechnique, not requiring cumbersome and expensive infrastructurecompared to other techniques. The electroless deposition technique alsoallows one to control the degree of reflectivity of light quiteaccurately and easily by varying the metal film thickness. Additionally,the known procedures are generalized procedures capable of beingutilized for coating a variety of surfaces. Furthermore, a layer of ametal or metal oxide can also be deposited onto any of the substrates bychemical vapor deposition from an appropriate precursor (The Chemistryof Metal CVD, edited by Toivo T. Kodas and Mark J. Hampden-Smith; VCHVerlagsgesellschaft mbH, D-69451 Weinheim, 1994, ISBN 3-527-29071-0).

[0022] The products of the present invention are useful in automotive,cosmetic, industrial or any other application where metal flake,pearlescent pigments or absorption pigments are traditionally used.

[0023] In the novel process for preparing the coated platelet-likesubstrates, the individual coating steps are each effected by knownprocedures such as by electroless deposition or hydrolysis/condensationof suitable starting compounds in the presence of the substrateparticles to be coated. For instance, the silver can be deposited fromreduction of its aqueous salts, such as AgNO₃ Silicon dioxide can bedeposited from silicon tetraalkoxides such as tetraethoxysilane, basessuch as sodium silicate and halide silanes such as silicontetrachloride; titanium dioxide from tetraalkoxides such as titaniumisopropoxide and titanium tetraethoxide, halide compounds such astitanium tetrachloride and sulfate compounds such as titanium sulfate,titanium nitride from titanium tetrachloride,tetrakis(diethylamido)titanium (TDEAT) andtetrakis(dimethylamido)-titanium (TDMAT); iron oxide from iron carbonyl,iron sulfate, iron nitrate and iron chloride; and chromium oxide fromchromium carbonyl and chromium chloride.

[0024] In general, the synthesis of the color effect material can be asfollows: a platelet material such as mica or glass flake is suspendedwhile stirring in an aqueous medium. The platelet substrate acts as acarrier substrate. It may, but usually does not, have a contribution oreffect on the final optical properties of the particulate. To thesuspension is added a metal precursor capable of depositing the desiredsilver metal on the substrate by electroless deposition, along with asuitable reducing agent. The resulting highly reflective silver metalcoated substrate is filtered, washed and re-suspended in an alcoholicmedium such as butanol. A Stöber process can be employed for thedeposition of a silicon dioxide spacer layer on the silver coated micaor other substrate (C. Jeffrey Brinker and George W. Scherer, Sol-GelScience, The Physics and Chemistry of Sol-Gel Processing, AcademicPress, Inc. (1990)). An alcoholic azeotropic mixture, such as ethanoland water, may be used in place of pure alcohol for the Stöber process.The silica encapsulated silver coated platelet is filtered, washed andre-suspended in a stirred aqueous medium. An aqueous solution of an ironsalt is added and the pH is changed to deposit the iron on the spacerlayer. Then to the aqueous medium, a metal solution for electrolessdeposition is added as described above allowing for the deposition of aselectively transparent metal coating. The final particulate product iswashed and dried.

[0025] The color effect materials of the invention are advantageous formany purposes, such as the coloring of paints, printing inks, plastics,glasses, ceramic products and decorative cosmetic and personal carepreparations. Their special functional properties make them suitable formany other purposes. The effect materials with a conductive outerlayer,for example, could be used in electrically conductive orelectromagnetically screening plastics, paints or coatings or inconductive polymers. The conductive functionality of these effectmaterials make them have great utility for powder coating applications.

[0026] Products of this invention have an unlimited use in all types ofautomotive and industrial paint applications, especially in the organiccolor coating and inks field where deep color intensity is required. Forexample, these effect materials can be used in mass tone or as stylingagents to spray paint all types of automotive and non-automotivevehicles. Similarly, they can be used on allclay/formica/wood/glass/metal/enamel/ceramic and non-porous or poroussurfaces. The effect materials can be used in powder coatingcompositions. They can be incorporated into plastic articles geared forthe toy industry or the home. These effect materials can be impregnatedinto fibers to impart new and esthetic coloring to clothes andcarpeting. They can be used to improve the look of shoes, rubber andvinyl/marble flooring, vinyl siding, and all other vinyl products. Inaddition, these colors can be used in all types of modeling hobbies.

[0027] The above-mentioned compositions in which the compositions ofthis invention are useful are well known to those of ordinary skill inthe art. Examples include printing inks, nail enamels, lacquers,thermoplastic and thermosetting materials, natural resins and syntheticresins. Some non-limiting examples include polystyrene and its mixedpolymers, polyolefins, in particular, polyethylene and polypropylene,polyacrylic compounds, polyvinyl compounds, for example polyvinylchloride and polyvinyl acetate, polyesters and rubber, and alsofilaments made of viscose and cellulose ethers, cellulose esters,polyamides, polyurethanes, polyesters, for example polyglycolterephthalates, and polyacrylonitrile.

[0028] For a well-rounded introduction to a variety of pigmentapplications, see Temple C. Patton, editor, The Pigment Handbook, volumeII, Applications and Markets, John Wiley and Sons, New York (1973). Inaddition, see for example, with regard to ink: R. H. Leach, editor, ThePrinting Ink Manual, Fourth Edition, Van Nostrand Reinhold(International) Co. Ltd., London (1988), particularly pages 282-591;with regard to paints: C. H. Hare, Protective Coatings, TechnologyPublishing Co., Pittsburgh (1994), particularly pages 63-288. Theforegoing references are hereby incorporated by reference herein fortheir teachings of ink, paint and plastic compositions, formulations andvehicles in which the compositions of this invention may be usedincluding amounts of colorants. For example, the effect material may beused at a level of 10 to 15% in an offset lithographic ink, with theremainder being a vehicle containing gelled and ungelled hydrocarbonresins, alkyd resins, wax compounds and aliphatic solvent. The effectmaterial may also be used, for example, at a level of 1 to 10% in anautomotive paint formulation along with other pigments which may includetitanium dioxide, acrylic lattices, coalescing agents, water orsolvents. The effect material may also be used, for example, at a levelof 20 to 30% in a plastic color concentrate in polyethylene.

[0029] In the cosmetic field, the effect materials can be used in allcosmetic and personal care applications subject, of course, to allregulatory requirements. Thus, they can be used in hair sprays, facepowder, leg-makeup, insect repellent lotion, mascara cake/cream, nailenamel, nail enamel remover, perfume lotion, and shampoos of all types(gel or liquid). In addition, they can be used in shaving cream(concentrate for aerosol, brushless, lathering), skin glosser stick,skin makeup, hair groom, eye shadow (liquid, pomade, powder, stick,pressed or cream), eye liner, cologne stick, cologne, cologne emollient,bubble bath, body lotion (moisturizing, cleansing, analgesic,astringent), after shave lotion, after bath milk and sunscreen lotion.

[0030] For a review of cosmetic applications, see Cosmetics: Science andTechnology, 2nd Ed., Eds: M. S. Balsam and Edward Sagarin,Wiley-Interscience (1972) and deNavarre, The Chemistry and Science ofCosmetics, 2nd Ed., Vols 1 and 2 (1962), Van Nostrand Co. Inc., Vols 3and 4 (1975), Continental Press, both of which are hereby incorporatedby reference.

[0031] Some illustrative examples of the invention will now be setforth. In these, as well as throughout this specification and claims,all parts and percentages are by weight and all temperatures are indegrees Centigrade, unless otherwise indicated.

EXAMPLE 1

[0032] One hundred grams of 100 micron glass flakes (100 micron averagemajor dimension) is placed in a 1 liter beaker equipped with a magneticstir bar and containing 393 grams of a 2% dextrose solution. The slurryis stirred at room temperature.

[0033] To the slurry is rapidly added a solution which is prepared asfollows: 7.87 grams of silver nitrate crystals are dissolved into 375 mldistilled water using a magnetic stirrer. A 29% solution of ammoniumhydroxide is added dropwise to the beaker resulting in a brownprecipitate which redissolves at a higher concentration of the ammoniumhydroxide solution. At the point where the solution becomes clear again,5 extra drops of the ammonium hydroxide solution is added to ensureexcess.

[0034] Several changes in the shade of the slurry occur as the reactionproceeds. After 15 minutes of stirring, the supernatant liquid is testedfor silver ion by the addition of a few drops of concentratedhydrochloric acid. The test is a visual assessment of any precipitateand/or turbidity of which none is found. The slurry is filtered andrinsed several times with distilled water and the presscake is dried at100° C. to a constant mass. The dried sample is a lustrous, opaque andsilver colored material.

[0035] A thin silica spacer layer is applied to the reflective metalcoated substrate as follows. In a 3 l flask, 600 g of the silver coatedborosilicate flake is slurried in 1028 ml of 2-propanol. To the slurryis added 8 ml of 29% ammonium hydroxide and 64 ml of distilled water.The mechanically stirred slurry is heated to 60° C., at which time 33.2g of tetraethoxysilane is added. After about 20 hours, the slurry iscooled, filtered, and washed with a few 100 ml aliquots of 2-propanol.The coated product is dried for 24 hours at 120° C.

[0036] The resulting silica-coated silver-coated borosilicate flakes(0.9 kg; average particle size 100 microns) are loaded into a horizontalcylindrical mechanical mixer equipped with mixing blades on a cantilevershaft. A sparger is introduced through the side of the reactor forintroduction of reactants. The reactor is heated to 200° C. and nitrogenis added at 168 standard cubic feet per hour (SCFH) through the door endof the reactor. Nitrogen is bubbled through a sealed reservoir of ironpentacarbonyl (IPC) at 5 SCFH resulting in an addition rate of 0.32g/min of IPC. This reagent flow is combined with an additional 238 SCFHof nitrogen as it enters the sparger which gives a total sparger gasflow of 243 SCFH. The run is continued for 5 hours to allow colorprogression advancements with the iron oxide layer thickness. A sampleis periodically removed from the reactor to assess the color progressionas a function of time.

EXAMPLE 2

[0037] 125 grams of silica-coated silver-coated glass flake (produced asset forth in Example 1) is slurried in 300 ml distilled water in a 1 Lround-bottom flask at 300 rpm and heated to 50° C. Then 300 ml of 0.19 MFe(NO₃)₃.9H₂O is added at 0.3 ml/min. while maintaining a pH of 4.0 with5% NH₄OH. At the end of the addition (approx. 16 hours), the sample isheated to 90° C. for 4 hours. The sample is then filtered hot, washedand dried at room temperature. The sample exhibits a unique goldenbronze color.

EXAMPLE 3

[0038] In a 3 l flask, 200 g of the silica-coated silver-coated glassflake (produced as set forth in Example 1) is slurried in 500 ml ofdistilled water and heated to 75° C. The pH is lowered to 5 using 15%acetic acid. A solution of 22.5% Fe(NO₃)₃.9H₂O is added at 0.25 ml/min.Once the pH reached 3.5, 10% NaOH is used to hold the pH constant.Approximately 400 ml of the iron(III) nitrate solution is added. Theresulting sample is filtered, washed, and dried at 200° C. yielding ahighly reflective gold colored effect material.

EXAMPLE 4

[0039] Example 3 is repeated except that approximately 600 ml of theiron(III) nitrate solution is added. The resulting sample is filtered,washed, and dried at 200° C. yielding a highly reflective golden orangecolored effect material.

EXAMPLE 5

[0040] Example 3 is repeated except approximately 800 ml of theiron(III) nitrate solution is added. The resulting sample is filtered,washed, and dried at 200° C. yielding a highly reflective golden orangecolored effect material.

EXAMPLE 6

[0041] A thin titania spacer layer is applied to a reflective metalcoated substrate as follows. In a 3 l flask, 100 g of silver coatedborosilicate flake prepared in Example 1 is slurried in 1200 ml ofethanol. To the slurry is added 1.14 g of 39% hydrochloric acid and 70ml of distilled water. Then 69 g of titanium tetraisopropoxide is addedto the mechanically stirred slurry. After about 24 hours, the slurry isfiltered, and washed with a few 100 ml aliquots of ethanol. The coatedproduct is dried for 24 hours at 200° C.

EXAMPLE 7

[0042] A thin titania spacer layer is applied to a reflective metalcoated substrate as follows. In a 5 1 flask, 100 g of silver coatedborosilicate flake prepared in Example 1 is slurried in 3600 ml ofethanol. To the slurry is added 3.42 g of 39% hydrochloric acid and 210ml of distilled water. Then 207 g of titanium tetraisopropoxide is addedto the mechanically stirred slurry. After about 24 hours, the slurry isfiltered, and washed with a few 100 ml aliquots of ethanol. The coatedproduct is dried for 24 hours at 200° C.

EXAMPLE 8

[0043] The electroless silver method of Example 1 is used to produce a 5nm thick silver third layer on 100 g of the product of Example 7.

EXAMPLE 9

[0044] Fifty grams of silver coated borosilicate flake prepared inExample 1 is placed in a 1 liter oven dried Morton flask containing 650ml of mineral spirits (boiling point 179-210° C.) previously dried overanhydrous magnesium sulfate. A condenser containing drierite desiccantis fitted to one neck of the 3-neck Morton flask with a stirring shaftand temperature probe fitted to the other two necks. The suspension isstirred at 250 rpm and heated to 100° C. To the heated suspension isadded 0.82 gram of benzoyl peroxide crystals followed by 7.4 grams ofdivinylbenzene (mixture of isomers). The reaction is allowed to stir at100° C. for 18 hours and then cooled to 45° C. The entire suspension isthen filtered on a Buchner funnel using #2 Whatman filter paper, rinsedwith ethanol and the product dried at 120° C. The resultingdivinylbenzene coating is visibly transparent and does not decrease thehigh reflectivity of the silver coated borosilicate flake.

[0045] Fifty grams of the polymer coated, silver coated borosilicateflake is slurried in 500 ml of ethanol. To the slurry is added 1.14 g of39% hydrochloric acid and 70 ml of distilled water. 69 g of titaniumtetraisopropoxide is added to the mechanically stirred slurry. After 20hours, the slurry is filtered, and washed with a 100 ml aliquot ofethanol. The coated product is dried for 24 hours at 95° C.

EXAMPLE 10

[0046] Ten grams of the product produced in Example 9 is dispersed in100 ml of distilled water in a 250 ml 3-neck flask. A stirring shaft, pHmeter and temperature probe are fitted to the 3-neck flask. Thesuspension is stirred at 250 rpm. To the suspension is added a colloidalsolution of 0.10 grams of tin chloride in 100 ml of distilled water.After 10 minutes of stirring, the suspension is filtered on a Buchnerfunnel and rinsed with distilled water. The rinsed presscake is thentransferred to a 250 ml 3-neck Morton flask fitted with a stirringshaft, pH meter and temperature probe. A solution of 1.0 grams ofdextrose in 75 ml of distilled water is added to the flask and stirredat 250 rpm. Through the temperature probe port of the flask a solutionof 1.0 grams silver nitrate in 100 ml of distilled water containing amolar excess of 2-amino-2-methyl propanol is added at 10 ml per minute.The reaction is stirred an additional 30 minutes, filtered on a Buchnerfunnel, rinsed with distilled water and dried at 120° C.

EXAMPLE 11

[0047] In a 1 liter flask, 50 g of product produced in Example 9 isslurried in 300 ml of distilled water, stirred at 200 rpm and heated to75° C. The pH is lowered to 5 using 15% acetic acid. A solution of 22.5%Fe(NO₃)₃.9H₂O is added at 0.25 ml/min. Once the pH reaches 3.5, 10% NaOHis used to hold the pH constant. Approximately 200 ml of the iron(III)nitrate solution is added. The resulting sample is filtered, washed, anddried at 95° C.

EXAMPLE 12

[0048] The effect material prepared according to example 1 isincorporated into polypropylene step chips at 1% concentration. The stepchips are appropriately named since they have graduating thickness ateach step across the face of the chip. The graduating steps allow one toexamine the different effect of the effect material based on polymerthickness.

EXAMPLE 13

[0049] The effect material prepared according to example 1 isincorporated into a nail enamel. 10 g of the effect material is mixedwith 82 g of suspending lacquer SLF-2, 4 g lacquer 127P and 4 g ethylacetate. The suspending lacquer SLF-2 is a generic nail enamelconsisting of butyl acetate, toluene, nitrocellulose,tosylamide/formaldehyde resin, isopropyl alcohol, dibutyl phthalate,ethyl acetate, camphor, n-butyl alcohol and silica and 127P is amoderately viscous, nitrocellulose lacquer containing butyl acetate,toluene, nitrocellulose, tosylamide/formaldehyde resin, isopropylalcohol, dibutyl phthalate, ethyl acetate, camphor, n-butyl alcohol andmethoxypropanol acetate.

EXAMPLE 14

[0050] In a similar fashion, a effect material prepared according toexample 1 is incorporated into a non-nitrocellulose based nail enamel.10 g of the effect material is mixed with 82 g of Avalure AC 315polymer, an acrylic polymer in ethanol, and acetone used in place ofnitrocellulose.

EXAMPLE 15

[0051] A 10% by weight effect material from example 1 is sprayed in apolyester TGIC powder coating from Tiger Drylac using a PGI corona Gun#110347. The effect material is mixed in a clear polyester system andsprayed over a RAL 9005 black powder sprayed base. The effect materialis highly attracted to the ground metal panel. Additionally, due to itshigh affinity to orient closely to the surface, it produces a finishthat is high in distinctness of image (DOI). It does not require anadditional clear coat to reduce protrusion often caused by traditionalpearlescent (effect) and metal flake pigments.

EXAMPLE 16

[0052] A 10% dispersion of the effect material prepared according toexample 1 is mixed into a clear acrylic urethane basecoat clearcoatpaint system DBX-689 (PPG) along with various PPG tints to achievedesired color. The tint pastes consist of organic or inorganic colorantsdispersed at various concentrations in a solventborne system suitablewith the DMD Deltron Automotive Refinish paint line from PPG. Thecomplete formulation is sprayed using a conventional siphon feedspraygun onto 4×12 inch (about 10×30 cm) curved automotive type panelssupplied by Graphic Metals. The panel is clear coated with PPG 2001 highsolids polyurethane clear coat and air dried.

[0053] Various changes and modifications can be made in the process andproducts of the invention without departing from the spirit and scopethereof. The various embodiments disclosed herein were for the purposeof illustration only and were not intended to limit the invention.

What is claimed is:
 1. A color effect material comprising aplatelet-shaped substrate sequentially encapsulated with: a first highlyreflective layer of silver; a second spacer layer which does not providesignificant incident angle dependent variable pathlength difference; andiron oxide.
 2. The color effect material of claim 1, wherein thesubstrate is selected from the group consisting of mica, aluminum oxide,bismuth oxychloride, boron nitride, glass flake, iron oxide-coated mica,iron oxide-coated glass, silicon dioxide, titanium dioxide-coated micaand titanium dioxide-coated glass.
 3. The color effect material of claim1, wherein the metal oxide layer is encapsulated by an outer layer thatis selectively transparent to light directed thereon.
 4. The coloreffect material of claim 4, wherein selectively transparent layer isselected from the group consisting of silicon, titanium dioxide,chromium oxide, aluminum, aluminum oxide and a mixed metal oxide.
 5. Thecolor effect material of claim 1, wherein the first layer is anelectroless silver deposition layer.
 6. The color effect material ofclaim 5, wherein the spacer layer is selected from the group consistingof silicon dioxide, magnesium fluoride, magnesium oxide, magnesiumhydroxide, aluminum oxide, aluminum hydroxide, titanium oxide andtitanium hydroxide.
 7. The color effect material of claim 6, wherein thespacer layer is silicon dioxide.
 8. The color effect material of claim1, wherein the spacer layer is a sol-gel deposition layer.
 9. The coloreffect material of claim 1, wherein the substrate is platelet-shapedmica or glass.
 10. The color effect material of claim 1, wherein thesubstrate is platelet-shaped mica, and the spacer layer is silicondioxide.
 11. A method of making a color effect material comprising:coating a platelet-shaped substrate with a first encapsulating layer ofhighly reflective silver; encapsulating the first layer with a spacerlayer which does not provide significant incident angle dependentvariable pathlength difference parent to light directed thereto; andencapsulating the spacer layer with an iron oxide layer.
 12. The methodof claim 11, wherein the substrate is selected from the group consistingof mica, aluminum oxide, bismuth oxychloride, glass flake, silicondioxide, iron oxide-coated mica, iron oxide-coated glass, titaniumdioxide coated glass and titanium dioxide-coated mica.
 13. The method ofclaim 12, wherein the spacer layer is selected from the group consistingof silver, gold, platinum, palladium, alloys of said metals, silicon,chromium oxide, a mixed metal oxide and aluminum.
 14. The method ofclaim 12, wherein the spacer layer is selected from the group consistingof silicon dioxide, magnesium fluoride, magnesium oxide, magnesiumhydroxide, aluminum oxide, aluminum hydroxide, titanium oxide andtitanium hydroxide.
 15. The method of claim 12, wherein the spacer layeris silicon dioxide.
 16. A cosmetic preparation containing a colorantwherein the colorant is a color effect material of claim
 1. 17. Acoating formulation comprising containing a colorant wherein thecolorant is a color effect material of claim
 1. 18. A plasticformulation containing a colorant wherein the colorant is a color effectmaterial of claim 1.